I'm having similar issues with my WP40 this week.
H1-H3 setting seem so much weaker than before.
With W1, it runs when I have the speed at S1 (100%) and S2 (75%) but also seems much weaker. At W1/S3 the impeller turns one time after plugging it in and then it gets stuck.
I already took it apart and gave it a vinegar bath and inspected the shaft to make sure there was no damage. Still no luck.
I'm not sure if the motor went bad or if it is a bad controller.
I am looking for my multimeter to see if somehow the controller is sending lower voltage than normal. It should be sending around 24v for full power, and 12v-13v at minimum.